Y. Jimbo

The University of Tokyo, Tōkyō, Japan

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Publications (49)45.64 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: Evaluating the accurate responses of the cardiovascular system to external stimuli is important for a deeper understanding of cardiovascular homeostasis. However, the responses should be distorted by the conventional time domain analysis when a frequency of the effect of external stimuli matches that of intrinsic fluctuations. Objectives: The purpose of this study is to propose a mixed signal processing of time domain and respiratory phase domain to extract the response waveforms of heartbeat and blood pressure (BP) to external stimuli and to clarify the physiological mechanisms of swallowing effects on the cardiovascular system. Methods: Measurements were conducted on 12 healthy humans in the sitting and standing positions, with each subject requested to swallow every 30 s between expiration and inspiration. Waveforms of respiratory sinus arrhythmia (RSA) and respiratory-related BP variations were extracted as functions of the respiratory phase. Then, respiratory effects were subtracted from response waveforms with reference to the respiratory phase in the time domain. Results: As a result, swallowing induced tachycardia, which peaked within 3 s and recovered within 8 s. Tachycardia was greater in the sitting position than during standing. Furthermore, systolic BP and pulse pressure immediately decreased and diastolic BP increased coincident with the occurrence of tachycardia. Subsequently, systolic BP and pulse pressure recovered faster than the R-R interval. Conclusions: We conclude that swallowing-induced tachycardia arises largely from the decrease of vagal activity and the baroreflex would yield fast oscillatory responses in recovery.
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    ABSTRACT: A novel co-culture device of neuronal cells was developed for analysis of cell interaction between a normal cell and an Alzheimer's disease infected cell. The device consisted of co-culture chamber system and a microelectrode arrays(MEA). The chamber system has a central chamber and three peripheral compartment chambers, connected by micro-channels. Rat hippocampal neurons were cultured separately in each of the peripheral compartment chamber. Neurites of the hippocampal neurons grow through the micro-channels to reach the central chamber and make connection. Formation of synaptic junction of the neuritis was confirmed by the imuunohistochemical staining. Electrical activities generated by hippocampal neurons network were recorded by the MEA, placed on the bottom of the three compartments. The results demonstrated the capability of this device for the analysis of pathogenic mechanism of Alzheimer's disease.
    Biomedical Engineering International Conference (BMEiCON), 2013 6th; 01/2013
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    ABSTRACT: The axon has a crucial role in the signal processing in the central nervous system. However, little is known about relationship between the structure of axons and conduction property of the axon. In this study, we developed a culture device to evaluate conduction velocity of relatively proximal (near the soma) and distal (far from the soma) parts of axons. The device has electrode units aligned at the bottom of the microtunnel structure. The electrode units enable the recording of action potentials of a single axon from three electrodes. Mouse cortical neurons were cultured in the device. The activity was recorded every five days. By employing an effective spike sorting method and a histogram method, propagating action potentials along the individual axon were successively detected from the spike trains which included the bursting activity. Finally, the change of the conduction delay at the distal part of axons was evaluated. The results show that our experimental system is feasible to study the conduction property of the axon.
    Neural Engineering (NER), 2013 6th International IEEE/EMBS Conference on; 01/2013
  • Y. Ogawa, K. Kotani, Y. Jimbo
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    ABSTRACT: The WM (working memory) is the essential element of intellectual work, thus the estimation of fatigue from neural activations in the WM task is important to control the stress with intellectual work. Furthermore, these WM evaluations from neural activities are useful for an improvement of diagnosis of psychiatric disorders. In this study, we investigate the relationship with the hemodynamic changes measured with Near Infrared spectroscopy during the WM task and the WM performance. Furthermore, we show the difference of the hemodynamics in delay time between correct-tasks and incorrect-tasks.
    Soft Computing and Intelligent Systems (SCIS) and 13th International Symposium on Advanced Intelligent Systems (ISIS), 2012 Joint 6th International Conference on; 01/2012
  • Journal of Biomechanical Science and Engineering 01/2010; 5(1):54-65. DOI:10.1299/jbse.5.54
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    ABSTRACT: Light addressing is an emerging and sophisticated technique that can induce pinpoint and/or patterned neuronal activation in cultured neurons. We previously developed a light-addressable electrode using hydrogenated amorphous silicon (a-Si:H), which was sandwiched between a tin oxide (SnO(2)) substrate and a passivation layer of zinc antimonate (ZnOSb(2)O(5)) dispersed epoxy. This research developed an experimental system that simultaneously implemented light-addressed stimulation and Ca(2+) imaging of neuronal activities. The translucent and thin laminated structure of our electrode permitted optical accesses from two directions: Ca(2+) imaging from above and light addressing from beneath. The submillisecond bright/dark switching property of our electrode offered light-addressed stimulation without causing interference with Ca(2+) imaging. To provide patterned illumination for light addressing, a digital micromirror device was installed in the system as an active photomask. The system could induce pinpoint neuronal activation at a cellular level.
    IEEE transactions on bio-medical engineering 07/2009; 56(11):2660-5. DOI:10.1109/TBME.2009.2024314 · 2.23 Impact Factor
  • Yasuhiko Jimbo
    IEEJ Transactions on Electrical and Electronic Engineering 11/2008; 3(6). DOI:10.1002/tee.20339 · 0.33 Impact Factor
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    ABSTRACT: Finger Braille is one of tactual communication media of deafblind people. Deafblind people who are skilled in Finger Braille can catch up with speech conversation and express various emotions. Because there are small non-disabled people who are skilled in Finger Braille, deafblind people communicate only with interpreters. Objective of this study is development of a Finger Braille supporting device which assists not only verbal communication but also non-verbal (emotional) communication between deafblind people and non-disabled people who are not skilled in Finger Braille. In this paper, to develop emotion recognition system, we analyzed features of emotional expression (Neutral, Joy, Sadness and Anger) and derived an algorithm of emotion recognition using accelerometers worn by receiver. According to the results of discriminant analysis, it was considered that emotion recognition using the discriminant functions by standardized data and the average of posterior probabilities in a sentence was possible and independent of sentences.
    Intelligent Information Hiding and Multimedia Signal Processing, 2008. IIHMSP '08 International Conference on; 09/2008
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    ABSTRACT: Finger Braille is one of tactual communication media of deafblind people. In one-handed finger Braille, a sender dots the left part of Braille code on the DIP joints of index, middle and ring fingers of a receiver, and then the sender dots the right part of Braille code on the PIP joints of them. Then the receiver recognizes the Braille code. Deafblind people who are skilled in Finger Braille can catch up with speech conversation and express various emotions. Because there are small non-disabled people who are skilled in Finger Braille, deafblind people communicate only with interpreters. In this paper, we developed a finger Braille recognition system. And evaluation experiments of recognition of monosyllables and sentences were carried out. As the results of the evaluation experiment of recognition of monosyllables, the accuracy of recognition of dotted fingers was 92.9% and the recognition system was independent of dotted strength, dotted position and receiver. The accuracy of recognition of dotted positions was 81.9% and the recognition system could recognize dotted positions if the receiver's hand shaped a natural longitudinal arch on the desk. As the results of the evaluation experiment of recognition of sentences, the accuracy of recognition of dotted fingers by dotting was 89.7% and the accuracy of recognition of dotted positions by dotting was 92.3%. Therefore the recognition system could recognize the sentences accurately when the interpreter dotted clearly. And the receiver should re-set his/her hand on the desk when he/she noticed cut-down of accuracy of recognition.
    Mechatronics and Automation, 2008. ICMA 2008. IEEE International Conference on; 09/2008
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    ABSTRACT: This paper describes an advanced Micro Channel Array (MCA) so as to record neuronal network at multiple points simultaneously. Developed MCA is designed for neuronal network analysis which has been studied by co-authors using MEA (Micro Electrode Arrays) system. The MCA employs the principle of the extracellular recording. Presented MCA has the following advantages. First of all, the electrodes integrated around individual micro channels are electrically isolated for parallel multipoint recording. Sucking and clamping of cells through micro channels is expected to improve the cellular selectivity and S/N ratio. In this study, hippocampal neurons were cultured on the developed MCA. As a result, the spontaneous and evoked spike potential could be recorded by sucking and clamping the cells at multiple points. Herein, we describe the successful experimental results together with the design and fabrication of the advanced MCA toward on-chip analysis of neuronal network.
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 02/2008; 2008:943-6. DOI:10.1109/IEMBS.2008.4649310
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    ABSTRACT: Finger Braille is one of tactual communication media of deafblind people. In two-handed Finger Braille, index finger, middle finger and ring finger of both hands are likened to keys of a Braille typewriter. A sender dots Braille code on the fingers of a receiver like whether he/she does the type of the Braille typewriter. Then the receiver recognizes the Braille code. In one-handed Finger Braille, the sender dots the left column of Braille code on the DIP joints of three fingers of the receiver, and then the sender dots the right column of Braille code on the PIP joints of them. Deafblind people who are skilled in Finger Braille can catch up with speech conversation and express various emotions. Because there are small nondisabled people who are skilled in Finger Braille, deafblind people communicate only with interpreters. Objective of this study is development of a Finger Braille supporting device which assists not only verbal communication but also nonverbal (emotional) communication between deafblind people and non-disabled people who are not skilled in Finger Braille. In this paper, an experiment of emotional expression of Finger Braille was carried out. And we analyzed features of emotional expression of Finger Braille and discussed algorithm of emotion recognition. The features of emotional expression were: (1) the durations of code of Joy were particularly shorter than other emotions; (2) the durations of code of Sadness were particularly longer than other emotions; (3) the finger loads of Anger were particularly bigger than other emotions. To develop emotion recognition system, we discussed algorithm of emotion recognition using the accelerometers worn by tester. According to the results of discriminant analysis, it was considered that emotion recognition using the discriminant functions and the average of posterior probabilities in a sentence was possible.
    12/2007: pages 484-487;
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    Y Jimbo
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    ABSTRACT: Based on the advantages of MEA-based recording, developmental changes of spontaneous activity and tetanus-induced modification of evoked activity were studied. Rat cortical neurons were cultured on MEAs and the spontaneous activity was continuously monitored for two months. The activity started a few days after plating. During the second week, the cultures generated periodic synchronized bursts, which were the characteristic properties of cortical neurons in vitro. In about one month, the cultured networks reached a steady state. Between these two, we found a critical period during which only weak activities were generated. This critical period might reflect the transition from immature networks to mature networks including precisely controlled excitatory and inhibitory synapses. We could elicit clear evoked responses with high reproducibility in mature cultures. A focal tetanic stimulation was applied to the mature cultures and how the tetanus affects 64 kinds of evoked activity was studied. The evoked responses showed bi-directional changes in their propagation patterns, potentiation and depression. These induced changes reflected the correlation properties with the tetanized activity pattern. The next step will be the combination of long-term recording and multi-site stimulation. How long does the induced change last, as well as how additional strong activity affects the previously induced changes, will be studied.
    Archives italiennes de biologie 12/2007; 145(3-4):289-97. · 1.42 Impact Factor
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    ABSTRACT: Finger Braille is one of tactual communication media of deafblind people. In finger Braille, index finger, middle finger and ring finger of both hands are likened to keys of a Braille typewriter. A sender dots Braille code on the fingers of a receiver like whether he/she does the type of the Braille typewriter. Then the receiver recognizes the Braille code. Deafblind people who are skilled in finger Braille can catch up with speech conversation and express various emotions. Because there are small non-disabled people who are skilled in finger Braille, deafblind people communicate only with interpreters. In this paper, we developed a finger Braille teaching system and designed a teaching interface which taught clauses explicitly. The teaching system recognized non-disabled people's speech and converted to Braille code. By parsing the Braille code, the teaching system retrieved clause information and segmented the Braille code into clauses. Then the dot pattern of the Braille code was displayed. By observing the dot pattern, non-disabled people dotted Finger Braille to deafblind people. An evaluation experiment between a blind person who was skilled in Finger Braille and two nondisabled people who were non-skilled in Finger Braille was carried out. The results showed that the fundamental functions (speech recognition, conversion to Braille code and clause segmentation) were practicable; the nondisabled senders could dot finger Braille accurately and communicate with the blind receiver directly. Therefore it was considered that the teaching system was effective.
    Mechatronics and Automation, 2007. ICMA 2007. International Conference on; 09/2007
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    ABSTRACT: In order to probe the spatio-temporal activity of cultured neural network, microelectrode arrays (MEAs) have been widely used. MEAs, however, have limitations of their electrode numbers and densities, resulting in low spatial resolutions of stimulation and recording. Here, to overcome this problem, we propose and develop an experimental setup for light-addressed stimulation and simultaneous fluorescence calcium imaging, using the previously published light-addressable electrode. The electrode has a translucent thin-film-laminated structure and allows optical access from both sides of the substrate. We, thus, provided the fluorescence excitation light from the topside and an addressing illumination from the bottom. By instantly shutting out the fluorescence excitation light during the stimulus application, we prevented the excitation light from interfering with the addressing illumination. With this experimental setup, we successfully measured spatio-temporal patterns of neuronal activities evoked by light-addressed stimuli. Evoked fluorescence transients with hundred-millisecond latencies suggested the possibility that some neurons were activated by recurrent synaptic inputs, which were possibly overlooked by previous MEA studies.
    Neural Engineering, 2007. CNE '07. 3rd International IEEE/EMBS Conference on; 06/2007
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    ABSTRACT: In the attempt to fully understand the mechanism for the formation and realization of tissue-specific functions of living multicellular systems, a couple of experimental conditions is required; grasping both the whole picture and the state of elements of a multicellular system. From this viewpoint, selecting neuronal circuits as the target, we have developed an electrical recording method from cultured small neuronal circuits by combining a simple micropatterning technique with a extracellular recording method using a mobile microelectrode. The simple micropatterning method enabled formation of thousands of individual small neuronal circuits consist of single to tens of neurons in one common 35-mm culture dish without any microfabrication apparatus by means of spraying of poly-D-lysine solution onto non-adhesive culture surfaces. Those small neuronal circuits, derived from embryonic hippocampus of rats, showed spontaneous synchronous firing after 8 days after cell seeding. Any of these small neuronal circuits were accessible with a mobile microelectrode, and their spontaneous firings were recorded noninvasively with single-cell-resolution by positioning the tip on constituent neurons. This set of methods does not require any specialized microfabrication apparatus or chemicals, and has a possibility to be used as a practical recording method of electrophysiological activities of a variety of multicellular organisms
    Neural Engineering, 2007. CNE '07. 3rd International IEEE/EMBS Conference on; 06/2007
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    ABSTRACT: Spontaneous electrical activity and intracellular calcium dynamics in dense cultures of rat cortical networks were simultaneously observed by using microelectrode array (MEA) and optical imaging system. At around one-week-cultures, periodical synchronized bursts, which are characteristic features of cultured cortical networks, were observed, and these synchronized bursts were followed by synchronized intracellular calcium transients among neural cells. After three weeks cultures, synchronized intracellular calcium transients were rarely observed in the cultured cortical networks although neurons showed distinct electrical activity with high frequency. As for the intermediate stage between these two states, we found slow, radial propagation of intracellular calcium waves were observed independent of the electrical activity of neural cells at around two-weeks cultures. The carriers of these calcium waves were suggested to be astrocytes from the result of pharmacological treatments of these cultured cortical networks. These results indicate that the dynamics of intracellular calcium in cortical networks changes depending on the developmental stages of cortical tissues, and astrocytes have characteristic roles in the development of functional cortical tissues as well as the spontaneous electrical activity of neurons.
    Neural Engineering, 2007. CNE '07. 3rd International IEEE/EMBS Conference on; 06/2007
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    ABSTRACT: Recently, Intra-Operative Magnetic Resonance Imaging (IO-MRI) has attracted attention for the reason of operating quality. In the other hand, surgical assist robot with high accuracy is widely researched. By combining IO-MRI and surgical assist robot to an MR-compatible surgical assist robot, higher quality of operation is expected. In this paper, we introduce a novel actuator for MR-compatible Surgical Assist Robot, which actively uses MR magnetic field and is drive by regulating pulse current. Use of ratchet mechanism enables step wise motion of the rotor similar to stepping motors. The position of the rotor can be controlled without an encoder. Clock-wise rotation, counter clock-wise rotation, constrained and non-constrained conditions were achieved by using this mechanism. Evaluation of the first prototype (84times76times58(mm<sup>3</sup>), 380 (gram)) shows that it is MR-compatible and has a very high positioning accuracy (step angle CW: 12.04plusmn0.28 (deg), CCW : 12.22plusmn0.36(deg); backlash < 1 (deg)). No-load maximum rotational speed is 35.71(rpm) and maximum torque 15.1times10<sup>-3</sup> (Nm).
    2007 IEEE/RSJ International Conference on Intelligent Robots and Systems, October 29 - November 2, 2007, Sheraton Hotel and Marina, San Diego, California, USA; 01/2007
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    ABSTRACT: This paper describes a new type of MCA (micro channel array) for simultaneous multipoint measurement of cellular network. Presented MCA is designed for advanced neural network analysis which has been studied by co-authors using 64 ch MEA (micro electrode arrays) system. First of all, sucking and clamping of cells through channels of developed MCA is expected to improve electrophysiological signal detections. Electrophysiological sensing electrodes integrated around individual channels of MCA are electrically isolated for simultaneous multipoint measurement.
  • 01/2007; 19(Supplement):127-127. DOI:10.5136/lifesupport.19.Supplement_127
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    ABSTRACT: Finger Braille is one of tactual communication medium of deafblind people. In two-handed Finger Braille, index finger, middle finger and ring finger of both hands are likened to keys of a Braille typewriter. A sender dots Braille code on the fingers of a receiver like whether he/she does the type of the Braille typewriter. Then the receiver recognizes the Braille code. Deafblind people who are skilled in Finger Braille can catch up with speech conversation and express various emotions. Because there are small non-disabled people who are skilled in Finger Braille, deafblind people communicate only with interpreters. In this study, we note one-handed Finger Braille. In one-handed Finger Braille, the sender dots the left column of Braille code on the DIP joints of three fingers of the receiver, and then the sender dots the right column of Braille code on the PIP joints of them. In this paper, we developed the Finger Braille Recognition System, which recognized deafblind people’s one-handed Finger Braille and converted to speech for non-disabled people. Non-disabled people wore small piezoelectric accelerometers on the base of index finger, middle finger and ring finger. The Recognition System detected the accelerations by dotting and recognized which fingers were dotted. Next, by parsing the recognized Braille codes, the Recognition System converted to a Japanese text. Finally, the Recognition System synthesized speech of the Japanese text. Because each accelerometer detected the acceleration by dotting of the mounted finger (self dotting) and the acceleration by dotting of the other fingers (cross talk). The Recognition System was necessary to recognize the acceleration by self dotting. We analyzed the accelerations dotted by an interpreter and derived the algorithm of recognition of dotted fingers. Estimated accuracy of recognition was 93.4%. Therefore it was considered that the algorithm was effective.
    12/2006: pages 2935-2938;

Publication Stats

1k Citations
45.64 Total Impact Points

Institutions

  • 2003–2012
    • The University of Tokyo
      • • Graduate School of Frontier Sciences
      • • Department of Precision Engineering
      Tōkyō, Japan
  • 2004
    • University of Cambridge
      • Department of Physiology, Development and Neuroscience
      Cambridge, England, United Kingdom
  • 1993–1998
    • Nippon Telegraph and Telephone
      Edo, Tōkyō, Japan
    • NTT DOCOMO
      Edo, Tōkyō, Japan